boulders, rubble, sand and mud. Between Bruthen and Tambo Upper there is extensive sedimentation with channel width exceeding , but a summer depth typically less than . Substrate in this section is all sand. The river narrows around Tambo Upper and the substrate becomes mainly mud beyond this point. Tributaries The Tambo River has a number of significant tributaries, with the two largest being the Little River which enters the Tambo from the north at Ensay, and the Timbarra River which enters the Tambo from the east, south-east of Tambo Crossing. The Tambo River South Branch, which originates on the Nunniong Plains in the hills east of Bindi, flows north to join the main river near its origin. The Tambo also has a number of more seasonal creeks entering along its length, including Swifts Creek which enters from the west at the town of the same name, Haunted Stream which enters from the west to the north of Tambo Crossing, with other minor tributaries including Junction Creek and Deep Creek. Ecology The central Tambo River area around Ensay and Swifts Creek have a mean annual rainfall of , with the lower section of the basin around Bruthen getting . Upper reaches of the significant tributary the Timbarra River typically get higher rainfalls. The Tambo and Timbarra have relatively reliable flows. There are some significant wetlands in the basin of the Tambo/Nicholson River systems. Flora The upper areas of the rivers include tall eucalyptus ash forests and alpine/subalpine vegetation, with the middle and lower reaches having a more low growing mixed species forest. The riparian vegetation in the Swifts Creek/Ensay region is largely grass and willows, with little erosion of the banks or sedimentation present. The riparian vegetation in the steep forest sections between Ensay and Bruthen is more natural, with wattles, eucalypts and other native species, while introduced species only become more prevalent again nearer to Bruthen. Fauna The nationally vulnerable Australian greyling has significant populations in the Tambo River. It is also a noted fishery for black bream. Low river flows that have been typical for a number of years have impacted on these species. The estuary perch is also common in the Tambo. Other fish that may be found in the river include native species such as the Australian bass, short-finned eel, long-finned eel, gudgeons, and the river blackfish, and introduced species such as brown trout and carp.